), although very little derstanding of their structure-activity relationship and biology is essential prior to its application. Some progress has already been made, and the effect of structural differences between SLs on AM fungal branching activity, parasitic weed seed germination and shoot branching have been demonstrated (Akiyama et al. 2010; Boyer et al. 2012, 2014; Yoneyama et al. 2009), Interestingly, SL specificity in transport in and ex planta has also been reported (Kohlen et al. 2012).